Extrusion apparatus

ABSTRACT

An extrusion apparatus comprising at least a first and second member forming a passageway, a die being held in position by an abutment closing the end of the passageway and a band means located against one wall of the passageway so as to form an antifriction device.

United States Patent 1 1 1111 3,911,705

Voorhes Oct. 14 1975 [5 EXTRUSION APPARATUS 3,349,153 10/1967 Beck72/351 3,740,985 6/1973 Fuchs, Jr. [75] Inventor: fi; gi East 3,765,21610/1973 Green 72/262 reenwic [73] Assignee: Wanskuck Company,Providence, FOREIGN PATENTS OR APPLICATIONS Rl 487,791 12/1953 Italy72/286 [22] Filed: 1974 Primary Examiner-Victor A. DIPalma [21] Appl.No.: 456,684 Attorney, Agent, or Firm-Bar1ow & Barlow [52] US. Cl.72/45; 72/92; 72/184; [57] ABSTRACT Int Cl 2 2532 An extrusion apparatuscomprising at least a first and i Second member forming a passageway adie being [58] Field of Search 1688; held in position y an abutmentClosing the end of the passageway and a band means located against onewall of the passageway so as to form an anti-friction de- [56]References Cited vice.

UNITED STATES PATENTS 2,602,538 7/1952 Bimba et a1 72 43 8 Clam, 6Drawmg Flgures US. Patent Oct. 14, 1975' Sheet 2 of2 3,911,705

/7II 5 A 5 Y F l G 4 y Ex riusioN' APPARATUS BACKGROUND or THE INVENTIONExtrusion broadly is the, process in which a piece of solid material isconverted into a continuous length of uniform cross section by forcingthe material to flow under high pressure through a die orifice which isso shaped as to impart the required form to the product. Untilrelatively recently the main form of extruding material in this generalpattern has been to do it as a hot operation, the material being heatedto a suitable degree of softness and plasticity to permit it to beforced through the orifice. More recently hydrostatic extrusion has comeinto our technology as represented by the Fuchs U.S. Pat. No. 3,740,985and a different approach has been described in ASME paper No. 73-WA/PT-2 and the Green U.S. Pat. No. 3,765,216. In the Green patent, afeed grip is utilized between a wheel and a shoe and the material isprogressively squeezed into a groove of the wheel against a die orifice.In processing material using the Green patent, heat is generated withinthe feed stock because of the sliding contact with the shoe member. Itis apparent that excessive temperatures may be achieved such as toanneal the material being extruded and turn out an inferior product. Itis therefore an object of the present invention to control the amount ofheat that is developed in this type of continuous extrusion apparatusand to reduce the power requirement.

SUMMARY OF THE INVENTION The present invention provides an improvementin the material extrusion process in which the metal is forced through adie means by frictional engagement of the metal in a groove orpassageway that is located within a wheel or block, the material beingretained in the groove by a shoe member that is held stationary withrespect to the wheel. In particular the improvement utilizes a bandmember that is located between the shoe and the walls of the groove andis held against the shoe by the feedstock. In this preferred embodimentthe band member is continuous. The band is normally moved by frictionalengagement between the feedstock and the band. In some cases the band isrestrained from such free movement. The degree of movement of the bandwith respect to the feedstock controls essentially the temperature risein the feedstock due to friction.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a detached perspective view of themain parts of the extrusion apparatus made in accordance with thisinvention;

FIG. 2 is a part sectional longitudinal elevational view of a modifiedform of extrusion apparatus made in accordance with the teachings ofthis invention;

FIG. 3 is a partial sectional view showing a detail of a modified formof shoe that is part diagrammatic indicating the source of fluid beingfed thereto by a pump;

FIG. 4 is a partial sectional elevational view of a modified form of theinvention;

FIG. 5.isa sectional view taken on lines 55 of FIG FIG. 6 is a detachedperspective view of the elemental form of the extrusion apparatus of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The extrusion apparatuscomprises a wheel 10 which is rotatably mounted on a shaft 12 that issuitably driven by a source of power (not shown) The wheel has acircumference 14 containing a passageway or groove 16, the groove takinga variety of forms of shape depending upon the type of feedstock beingextruded. Fitting closely within the groove 16 of the wheel is a shoemember 18 which is suitably anchored in position relative to the axis ofrotation of the shaft 12 and this shoe member has an arcuate mating edge20 which substantially conforms to the curvature of the bottom wall ofthe groove. An abutment member is suitably anchored in position relativeto the axis of rotation of the shaft 12 and has a projecting portion 26with a nose 27 that is shaped to fit within a groove 16 of the wheel 10.On the end of the nose 27 is a die insert 28 which has an orifice 29therein ofa shape of the product to be extruded and the projectingportion 26 and 27 together with the anchor means in the form of a block30 are formed with a thru bore 31 so that the material extruded throughthe orifice 29 may pass through the abutment block 30. Against thearcuate surface 20 of the shoe 18 is a band 35 which effectively closesthe groove 16 so as to provide the closure wall thereof and this band 35passes between the side walls 17 of the groove 16 of the wheel 10 andbears against the arcuate surface 20 of the shoe 18. Band 35 may be madecontinuous as shown in which case it is fed around guide pulleys 37, 38,39. Since the band forms the closure for the groove 16 it will beapparent that the material M as seen in FIG. 2 will bear against thisband and create a frictional drag thereon normally moving the band inthe direction of rotation of the wheel 10 as seen by the arrow A. It isdesirable that the band be provided with some lubricant on the surfacethereof that faces the arcuate surface 20 of the shoe 18 and thislubricant can take the form of a number of greases such as the sodiumseries of greases or the EP greases.

Reference should now be made to FIG. 3 where a modified form of shoe 18is disclosed, this shoe having a recess in its arcuate surface 20' whichrecess is designated 40. The recess comprises a central longitudinalgroove of a length substantially the length of the contacting surface 20which communicates with a number of bores 42 that lead to a pump 43 thatis connected to a source of fluid such as air or oil. In effect fluidwhich is fed under pressure to the groove provides a bearing for theband 35, such fluid being used as a lubricant so as to maintain the band35 and the arcuate surface of shoe out of direct contact by developing afilm of fluid under compression underneath the band 35. In effect, thefilm of fluid operates in the same fashion that a hydrostatic bearingoperates, the fluid escaping out under the edge of the band 35 whre thesame is guided between the side walls of the groove.

It is also desirable in some cases to control the temperature of thestock that is being extruded. If the speed of the band 35 is the same asthe speed of the feedstock, then there will be substantially no frictionforces to increase the temperature of the stock being extruded. On theother hand if it is desired to raise the temperature of the stock beingextruded, then the speed of the band 35 may be varied with respect tothe feedstock and to this end a caterpillar drive generally designated50 may be provided, the caterpillar drive being made similar to thecaterpillar drives used widely in wire handling field and may be madesubstantially in accordance with US. Pat. No. 2,776,832. It will beunderstood that a separate drive means for the caterpillar may beprovided or a variable speed coupling provided to the main shaft 12.

Referring now to FIGS. 4 and 5, there is shown a modification of theinvention in which there will be less distortion of round feedstock thanin the squaregrooved version represented in FIGS. 1-3. The wheel "isprovided with a groove 16" which is of substantially circular sectionwith the center radius thereof as at r positioned radially inward of thecircumferential surface of the wheel 10 so as to yield for a partialdistance side walls 17" that are tangent to the circle cross section.The shoe 18" has a groove 50 therein which complements the circularcross section of the groove 16" of the wheel so as to provide a gripthereon, the feedstock yielding and upsetting to fill the cross section.The band 35" that is utilized between the feedstock and the show 18" issuch that it will conform to the shape of the groove 50 due to itsinherent flexibility and will reduce the friction of the feedstock byvirtually eliminating the frictional drag on the shoe. In all otherrespects this modification is similar to that previously described inconnection with FIG. 1.

Refer now to FIG. 6. Essentially the use of a wheel is a practical formof a continuous process device which in its elemental form comprises ablock 10A having a groove or passageway 16A, an abutment A and shoe 18Aupon which band A rests. Stated in other terms, the passageway 16A maybe defined by the walls of a pair of first members 62, 63, a second shoemember 18A and a third plate member 60. Such a device is useful fordiscontinuous extrusions and it will immediately be apparent that thefirst and third members are coupled together for movement while thesecond member and the abutment are stationary.

It will be understood that this apparatus operates substantially in thesame manner as that disclosed in US Pat. No. 3,765,216. The differencebetween the operation of the instant device and the Green patent lies inthe fact that the feedstock does not press directly against the arcuatesurface 20 of the shoe member 18 but against the band 35 that bearsagainst the arcuate surface 20 of the shoe member and the groove 16. Thematerial M is carried toward the die member 28 by frictional drag of theside walls 17 and the bottom wall of groove 16. It will be apparent thatthere are frictional forces set up on each of the four contacting sidesof the material M. Three of the sides are aiding motion of the materialand only one is resisting, that is the side which now contains the band35. It is this fourth side of the member in the Green patent whichcreates considerable friction and resulting power loss and gives rise toa significant temperature increase in the feedstock. Additionally, byeliminating the fourth side drag, various groove configurations arepossible. As explained by Green in his US. Pat. No. 3,765,216 and thearticle in Journal of the Institute of Metals 1972, Vol. 100, p. 295,the compressive stress on the feedstock does not exceed the yieldstrength of the feedstock where the feedstock enters the passageway.However, the compressive stress on the feedstock in the die region willexceed the yield strength of the feedstock, causing the feedstock toyield and upset P ZY ara 3 Since the force to overcome friction alonglength I can be expressed where p. is the coefficient of frictionbetween the feedstock and the shoe therefore P Fnu'Tlox Pun 2 3 Thetotal force required both to extrude and to overcome shoe friction canbe expressed:

TOTAL EXTRL'SIOA FRICTION If the groove/shoe cross section is square,then FTOTAL =PW PW (P/Y 2) u/S I claim:

1. Extrusion apparatus comprising a passageway formed between twoopposing walls in a first member, the bottom of the passageway beingclosed by a surface of a second member, said surface having lubricantthereon, the top of the passageway being closed by a third member, anabutment extending into the passageway and closing an end thereof, a dieinsert positioned against the abutment, a continuous band being guidedfor movement on the lubricated surface of the second member about theapparatus, the surface wall area of the first member being greater thanthe surface area of the band lying against the third member, means forfeeding material to be extruded to said passageway, said materialbearing against said band and moving the same toward said abutment.

2. Extrusion apparatus comprising first and second members forming apassageway therein, said first member providing means forming a groove,said second member closing the groove, by means defining a surface,lubricant on said surface, an abutment at one end of the passageway, adie insert held by the abutment, and a continuous band being guided bythe first member about the apparatus and bearing on a lubricated surfaceof the second member facing the passageway, means for feeding materialto be extruded to said passageway, said material bearing against saidband and moving the same toward said abutment.

3. Extrusion apparatus as in claim 2 wherein said first member is awheel and the second member is a shoe facing the bottom wall of thegroove.

4. Extrusion apparatus as in claim 2 wherein the arcuate surface of theshoe member is concave in cross section.

5. Extrusion apparatus comprising first and second members forming apassageway, said first member being a wheel with a groove therein, saidgroove having side and bottom walls, the second member having a surfaceclosing the groove of the first member, an abutment extending into thepassageway and closing an end thereof, a die insert positioned againstthe abutment and a continuous band being guided for movement on thelubricated surface of the second member about the apparatus, the surfacewall area of the first member being greater than the surface area of theband lying against the third member, means for feeding material to beextruded to said passageway, said material bearing against said band andmoving the same toward said abutment.

6. Extrusion apparatus as in claim 5 wherein said first member is awheel and the second member is a shoe tween the band and the supportmeans therefor.

I l l l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3 911, 705

Dated October 14. 1975 Inventor-(s) William G. VOOIheS It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

In the specification line 21 of column 4, please correct the formula toread as follows:

F '=Pw -+2 A FRiCTlON Y 3 Signed and Sealed this Arrest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner ofParentsand Trademarks

1. Extrusion apparatus comprising a passageway formed between twoopposing walls in a first member, the bottom of the passageway beingclosed by a surface of a second member, said surface having lubricantthereon, the top of the passageway being closed by a third member, anabutment extending into the passageway and closing an end thereof, a dieinsert positioned against the abutment, a continuous band being guidedfor movement on the lubricated surface of the second member about theapparatus, the surface wall area of the first member being greater thanthe surface area of the band lying against the third member, means forfeeding material to be extruded to said passageway, said materialbearing against said band and moving the same toward said abutment. 2.Extrusion apparatus comprising first and second members forming apassageway therein, said first member providing means forming a groove,said second member closing the groove, by means defining a surface,lubricant on said surface, an abutment at one end of the passageway, adie insert held by the abutment, and a continuous band being guided bythe first member about the apparatus and bearing on a lubricated surfaceof the second member facing the passageway, means for feeding materialto be extruded to said passageway, said material bearing against saidband and moving the same toward said abutment.
 3. Extrusion apparatus asin claim 2 wherein said first member is a wheel and the second member isa shoe facing the bottom wall of the groove.
 4. Extrusion apparatus asin claim 2 wherein the arcuate surface of the shoe member is concave incross section.
 5. Extrusion apparatus comprising first and secondmembers forming a passageway, said first member being a wheel with agroove therein, said groove having side and bottom walls, the secondmember having a surface closing the groove of the first member, anabutment extending into the passageway and closing an end thereof, a dieinsert positioned against the abutment and a continuous band beingguided for movement on the lubricated surface of the second member aboutthe apparatus, the surface wall area of the first member being greaterthan the surface area of the band lying against the third member, meansfor feeding material to be extruded to said passageway, said materialbearing against said band and moving the same toward said abutment. 6.Extrusion apparatus as in claim 5 wherein said first member is a wheeland the second member is a shoe facing the bottom wall of the groove. 7.Extrusion apparatus as in claim 5 wherein the arcuate surface of theshoe member is concave in cross section.
 8. A process of extrudingmaterial comprising feeding solid stock material into a passagewayformed between a band and a groove in another member, moving the othermember, providing die means closing one end of said passageway,providing means to support the band , moving the band at the input feedspeed of the solid stock and providing continuous lubrication betweenthe band and the support means therefor.